Hi Brian,
I recommend you to download the current version of the controls and to convert your custom handler to be compatible with the latest RadUploadHandler. If you have any problems - please send us a project we will see what the problem is.
BTW: with our latest release we added new examples for RadUpload. Check them online here:
http://demos.telerik.com/silverlight/
All the best,
Valentin.Stoychev
the Telerik team
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